Laserfiche WebLink
v1117 Lone Palm Avenue, Suite B <br /> A Modesto, CA 95351 <br /> www ate-enviro com <br /> c °� ,;, H11-Al-III 209 579 2221 <br /> r <br /> r" <br /> IJ, 7 r j +��_ Fax 209 579 2225 <br /> A S S O C I A T E S 1 N C <br /> 3 <br /> rile 641 <br /> December 2, 2003 La -9 a <br /> 54 62605 0001 �� '0 .� 1 <br /> Ms Vicky McCartney <br /> San Joaquin County <br /> Environmental Health Department <br /> 304 E Weber Avenue, Third Floor <br /> Stockton, California 95202 <br /> I <br /> Subject Monitoring Report - Third Quarter 2003, Former Thiemann's Service Station, 106 West <br /> Second Street, Ripon, California <br /> Dear Ms McCartney <br /> This report presents the results of quarterly groundwater monitoring and sampling performed in July 2003 <br /> by ATC Associates Inc at the former Thiemann's Service Station The site is located at 106 West Second <br /> Street in Ripon, California (Figure 1) Sampling was performed to monitor the distribution of petroleum <br /> hydrocarbons in groundwater at the site and to determine the groundwater flow direction and magnitude of <br /> • the hydraulic gradient in the uppermost aquifer <br /> SITE HISTORY <br /> In March 1991, three underground storage tanks (UST's) were removed from the site Analysis of soil <br /> samples collected from the excavation indicated that high concentrations of petroleum hydrocarbons were <br /> present in soil beneath the tanks Groundwater was not encountered in the excavation The location of the <br /> former UST's is shown on Figure 2 <br /> In July 1993, a subsurface investigation was conducted at the site to determine the extent of petroleum <br /> hydrocarbons present in soil and to determine if groundwater had been impacted The investigation <br /> included drilling eight soil borings and collection of soil samples Three of the borings were completed as <br /> shallow groundwater monitoring wells (MW-1, MW-2 and MW-3) Analyses of soil samples indicated <br /> that the greatest concentration of petroleum hydrocarbons in soil occurred from approximately 10 feet <br /> below ground surface (bgs) to the groundwater surface at a depth of approximately 29 feet bgs and within <br /> a radius of 35 feet from the former UST pit <br /> In August 1993, monitoring wells MW-1, MW-2, and MW-3 were monitored and sampled Laboratory <br /> analytical results indicated that wells MW-2 and MW-3 contained detectable levels of petroleum <br /> hydrocarbons in the groundwater The sample collected from MW-1 was reported to contain no measurable <br /> concentrations of petroleum hydrocarbons A program of quarterly groundwater monitoring and sampling <br /> was initiated in March 1994 <br /> In August 1995, Smith Technology conducted a subsurface site investigation to further define the extent of <br /> contamination in groundwater at the site Smith Technology supervised the nistallation of monitoring wells MW- <br /> w lwordpro1626051quaAiy\3QR-2003 doc I <br /> ENVIRONMENTAL, GEOTECHNICAL AND MATERIALS PROFESSIONALS <br />